Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/17/24
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
948 PM EDT Fri Aug 16 2024
.SYNOPSIS...
Scattered showers and storms are possible through Monday as an upper
level trough moves into the area. Cooler and drier conditions are
expected from Tuesday through the rest of next week as high pressure
remains to the north of the local area under a trough aloft.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 945 pm EDT Friday...
No major changes to the going forecast. Showers over the
Piedmont and Blue Ridge have all but dissipated as they moved
east and into the drier airmass. However, dew points are
starting to creep up across the area this evening with most
areas in the mid-upper 60s. Latest HRRR is not terribly excited
about prospects of precip overnight as the short wave currently
over the Ohio Valley moves east. Still, given the increased dew
points and the isolated showers already developing over the
mountains, I do not want to decrease PoPs considerably.
However, I have delayed the highest PoPs into the I-95 corridor
until late tonight.
As of 355 PM EDT Friday...
Key Messages:
- Scattered showers and perhaps an isolated storm or two are possible
late tonight into early Saturday morning.
Afternoon sfc analysis depicts high pressure off the East Coast.
Aloft, a weak ridge moves E across the Great Lakes with a trough off
the East Coast moving E. Temps as of 320 PM range from the mid-upper
80s with highs in the upper 80s for most (potentially around 90F at
Richmond). Lows tonight in the upper 60s to around 70F expected for
most with mid-upper 60s possible across SE VA/NE NC and the Eastern
Shore (where less cloud cover is expected). Dry this afternoon.
However, a shortwave moves E tonight into Sat morning with scattered
showers (and perhaps an isolated storm or two) possible overnight.
Greatest confidence is along the I-95 corridor (40% PoPs). Given the
increase in cloud cover, lows tonight will likely be coolest across
the SE (where less cloud cover is expected) and warmest in the
Piedmont with lows in the upper 60s (mid 60s across the SE) to lower
70s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
As of 355 PM EDT Friday...
Key Messages:
-Seasonally warm and humid with daily chances for scattered
showers and storms.
-Storms may be strong to severe Saturday and Sunday with a
better chance for more widespread convection on Sunday.
Aloft, an upper level low slowly moves from the Great Lakes to the
East Coast Sat-Mon, gradually losing it`s circulation and becoming a
trough. Meanwhile, a series of shortwaves rounds the base of
trough/upper level low creating daily chances for showers/storms. At
the surface, a cold front slowly approaches from the Ohio Valley Sat-
Sun before crossing the local area Sun night into Mon.
Ahead of the trough/cold front, humidity increases with dew points
in the low-mid 70s Sat and Sun. Dew points still remain elevated Mon
(upper 60s to around 70F), particularly across E portions of the FA.
Temps are expected to rise into the mid-upper 80s each day with heat
indices in the low-mid 90s (highest Sun with 90-97F heat indices).
CAMs show uncertainty with respect to timing of convection Sat with
the HRRR showing multiple rounds of convection through the day and
the NAM 3km showing the late afternoon lee trough convection
dissipating before making it to the I-95 corridor. Have therefore
gone with a blended approach, anticipating the potential for at
least two main rounds of convection (the morning round and the late
afternoon/evening lee trough round). As such, have chance PoPs
through the day (30-50%) with the highest confidence late Sat
afternoon into Sat evening with the lee trough convection moving E
in the form of a line. Synoptically, it makes sense that any
convection forming off the lee trough should become organized into
linear segments and move E, likely sustaining to at least the
I-95 corridor given HREF mean CAPE around 1000 J/kg (max values
are around 2000 J/kg). Expect storms to weaken as they approach
the coast given lessening CAPE values. A few additional isolated
showers/storms are possible overnight Sat night, but confidence
is low in coverage. Additionally, given sufficient CAPE and
0-6km shear of 25-30 kt, some storms may be strong to severe
with strong to damaging winds the primary threat. SPC has areas
along and W of I-95 in a marginal risk (level 1/5) for severe
weather.
The upper level trough moves over the area Sun providing synoptic
forcing sufficient for more widespread scattered showers and storms
during the afternoon and evening. In addition to the forcing aloft,
a cold front moves E towards the local area late Sun afternoon into
Sun night. As such, have increased PoPs to likely (60%) Sun
afternoon with PoPs quickly tapering off Sun night as the cold
front slowly moves through. Similar to Sat, 0-6km shear of 25-30
kt (locally 35 kt) is expected with higher CAPE (MLCAPE of
1500-2000 J/kg+). Given higher instability, greater forcing, and
decent shear (for mid August), expect the potential for
scattered strong to severe storms with damaging winds the
primary threat. SPC has a marginal risk (level 1/5) for the
entire FA and clips portions of NE NC in a slight (level 2/5)
risk. Would not be surprised if the slight gets expanded NE in
the future updates. While storms should be moving given 25-30
kt+ of deep layer shear, cannot rule out localized flooding,
particularly if storms train over the same areas. As such, WPC
has areas N of I-64 in a marginal risk for excessive rainfall
Sat and the entire area under a marginal risk on Sun.
The upper level trough remains over the area on Mon with a final
shortwave pushing through Mon afternoon into Mon evening.
Instability (MLCAPE of 500-1000 J/kg) will be lower but still
sufficient for widespread scattered showers and perhaps isolated
storms. However, given WSW sfc winds behind the cold front, severe
weather is not anticipated at this time. That being said, cannot
rule out some gusty winds (30-45 mph) with any showers given
steepening mid level lapse rates (~6.5C). Any showers taper off
quickly by Mon evening. Lows are expected to range from around 70F
Sat night, mid-upper 60s W to lower 70s E Sun night, and lower 60s W
to upper 60s E Mon night.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 405 PM EDT Friday...
Key Messages:
-Cooler, drier weather is expected next week.
A seasonally strong upper level trough remains over the East Coast
through next week with high pressure centered to the N of the local
area. This will allow for a prolonged period of cool and dry weather
with below normal temps expected from Tue-Fri. Highs range from
around 80F Tue-Thu and low-mid 80s Fri with lows in the mid-upper
50s W to the mid-upper 60s along the coast Tue and Wed nights, upper
50s to around 60F W to the mid-upper 60s E Thu night, and lower 60s
W to upper 60s to around 70F E Fri night. Wed and Thu mornings look
to be very pleasant with widespread temps in the upper 50s possible
inland (away from urban areas). Additionally, dew points drop behind
the cold front on Tue into the upper 50s to lower 60s and remain in
the mid 50s to lower 60s through late week. Mainly dry weather is
expected through the week apart from a low chance for an isolated
shower or storm across the N Tue afternoon.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
As of 730 PM Friday...
A weak disturbance moves through the area tonight into Saturday
morning. Showers over the Piedmont and mountains may reach RIC
overnight, but there is simply not enough confidence to include
in the terminal forecast. More likely, MFVR cigs will develop
early Saturday morning at RIC as low level moisture increases.
However, guidance suggests the reduced CIGS will be short lived
as they raise to VFR by 18z. Showers/storms are possible
tomorrow afternoon especially at RIC from the lee side trough.
Southeast winds of 5 to 10 kt tonight becoming southerly on
Saturday.
Outlook: A slow moving cold front will approach from the west
Sunday into Monday with chances for scattered aftn/evening
showers/storms each day, especially Sunday. Storms may be strong
to severe on Sunday with gusty winds the primary threat.
&&
.MARINE...
As of 355 PM EDT Friday...
Key Messages:
- Small Craft Advisories are in effect for all coastal waters starting
tonight north of Cape Charles, with the remaining coastal
waters and the Mouth of the Bay starting on Saturday as swells
from Hurricane Ernesto reach the coast.
- SCAs remain a possibility in the Bay Sat aftn/Sat night for southerly
wind gusts of 20 - 25 kt with the best chance N of New Pt
Comfort.
The area of high pressure that has been in place for the last several
days is gradually weakening and sliding off the New England Coast
this afternoon. Meanwhile, a storm system over the Great Lakes is
making slow progress toward the Mid-Atlantic States today and will
take several days to move through the area, before departing early
next week. Right now Winds are generally from S at 5-10 kt but are
stating to increasing from the S - SE. As the area of high pressure
slides offshore and the low pressure system approaches from the
midwest, expect to see enough tightening of the pressure gradient
for S winds 10-15kt with gusts to 20 kt tonight, and winds a little
higher Sat aftn/Sat night. SCA conditions from wind are possible in
the Ches Bay north of New Pt Comfort. Meanwhile, Hurricane Ernesto,
currently about 180 miles SW of Bermuda, is forecast to lift NNE,
over Bermuda by early Sat before heading into the North Central
Atlantic. Impacts locally will be restricted to increasing swell and
the threat for deadly rip currents. SCA flags start for the Atlantic
waters north of Cape Charles Light at 02z/10pm tonight, with the
remaining Atlantic waters and the mouth of the Bay starting SCAs by
Sat aftn. Seas Saturday will average 5-7 ft N of Cape Charles, and 4-
5 ft to the south, while then averaging 5-6 ft by late Sat night
through Sunday. Waves near the mouth of the bay will increase as
well, generally 2-3 ft on Saturday with 3-5 ft possible late Sat
night into Sunday before things start to calm down Monday (though
will likely have seas offshore linger at 4-5 ft possibly into early
Tuesday). The models are in decent agreement that another eastern
CONUS upper trough develops next week, allowing a cold front to move
through the local waters Mon night/Tuesday with winds shifting to
the N/NW. Current models do not show more than 10-15kt of wind Mon
night/Tue, but as the details become more precise, would expect
winds to be stronger given good mixing as rather cool air (by August
standards) moves over the warm waters.
&&
.TIDES/COASTAL FLOODING...
As of 420 AM EDT Friday...
Key Message:
- A Moderate Risk of Rip Currents today, with a High Rip Risk
likely for both Saturday and Sunday as long period swell from
distant Hurricane Ernesto affects the region.
The latest 16/00Z run of the NWPS supports high rip risk for
all Atlantic coastal zones for the weekend given seas of 4-6 ft
with a dominant period of 13-15 seconds. Today begins low with
seas only 1-2 ft, but with the building seas to ~3 ft or 3-4 ft
this aftn, and an increase in the wave period, will have a
Moderate rip risk in effect today. Some minor tidal flooding
will be possible along the Bayside of the MD eastern shore by
Sun/Mon as the persistent long period swell may help trap water
in the Bay for several tide cycles (the southerly wind direction
favors transporting any trapped water northward).
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 2 PM Saturday to 6 AM EDT Monday for
ANZ634.
Small Craft Advisory until 6 AM EDT Monday for ANZ650-652-654.
Small Craft Advisory from noon Saturday to 6 AM EDT Monday for
ANZ656-658.
&&
$$
SYNOPSIS...RMM
NEAR TERM...RMM/MRD
SHORT TERM...RMM
LONG TERM...RMM
AVIATION...RMM/MRD
MARINE...ESS/LKB
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service La Crosse WI
1055 PM CDT Fri Aug 16 2024
.KEY MESSAGES...
- Showers and isolated storms continue for the rest of this afternoon
and into the evening hours. Additional chances (20-40%) for
showers persist for Saturday afternoon.
- Temperatures through next week will likely trend near to
slightly below average for this time of year with relatively
minimal precipitation chances.
&&
.DISCUSSION...
Issued at 233 PM CDT Fri Aug 16 2024
Today - Saturday: Seasonably Mild with Showers and Isolated Storms
The overall synoptic setup this afternoon revolves around a
vertically stacked upper-level to surface low centered across north-
central Wisconsin. Pivoting around this feature are several subtle
shortwaves aiding in instigating showers and storms with the overall
mesoscale environment featuring two distinct modes across the local
area this afternoon. Where low-level moisture has maintained with
dewpoints in the upper 60s to around 70, MUCAPE values remain
elevated enough (1000-2000 J/kg) to support more vigorous convection
as seen late this morning in Clark and Jackson counties. West of the
Mississippi River, increasing cloud cover and lower dewpoints have
minimized the amount of instability present. Consequently, would
expect the predominant mode of precipitation to be showers with a
low-end chance for a rumble of thunder or two west of the
Mississippi River. The potential for funnels throughout the
afternoon generally has trended less likely with guidance lacking a
surface feature to really latch onto as a subtle boundary pushes
east of the local area. As a result, have noted fairly low values in
the non-supercell tornado parameter in the 16.15z RAP for the local
area. Regardless, as cloud cover pushes east with the cyclonic flow,
instability will begin to wane favoring a more showery environment
into the evening hours for much of the local area with showers
gradually dispersing by sunset.
As we head into Saturday, the upper-level low continues to push
southeast through the Great Lakes. With a more northwesterly flow
regime and cloud cover overhead, temperatures will trend on the
milder side with highs in the middle to upper 70s across the region.
With additional weak pieces of upper-level energy behind the upper-
low, much of the CAMs still paint some shower coverage for the
afternoon on Saturday. A rumble of thunder or two cannot be ruled
out with MLCAPE values of up to around 500 J/kg in the 16.15z RAP.
Similar trend for Saturday as today with showers waning in coverage
later into the evening hours as well.
Sunday - Friday: Continued Slightly Below Average Temperatures
Looking into next week, our region is situated between two broad
synoptic features with a large upper-level ridge to the west and a
trough to the east. Consequently, our region is once again stuck in
northwesterly flow which will aid in keep our temperatures slightly
below normal through next week with median high temperatures of
middle 70s to lower 80s in the 16.00z grand ensemble (GEFS/EC
ens/Canadian ens) with little inter-quartile spread amongst
ensemble members. Precipitation chances appear minimal into next
week with any shortwaves riding over the aforementioned ridge
being the main source of any precipitation potential which long-
range guidance currently does not reflect. Regardless, with the
16.00z grand ensemble (GEFS/EC ens/Canadian ens) having very low
joint CAPE (over 500 J/kg) and shear (over 30 kts)
probabilities of under 20% through the middle of the week, any
organized severe weather appears unlikely at this time.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1055 PM CDT Fri Aug 16 2024
Main aviation weather concerns will revolve around low stratus
tonight into Saturday along with areas of fog. Latest
observations show patchy MVFR to IFR ceilings developing around
the region. This will expand through the early morning hours
given the abundant moisture in place. There remains a 60 to 90%
chance for IFR ceilings at RST and LSE, with about a 30 to 50%
chance for LIFR. Less certain is the potential for patchy fog,
though RST stands the better chance for MVFR to IFR visibility.
Flight categories are expected to be lowest around sunrise, with
gradual improvement through late morning as daytime heating gets
underway. This will also lead to potential for scattered
showers heading into Saturday afternoon and evening. Ceilings
should return to VFR by early to mid afternoon. Winds through
the period will be generally out of the northwest around 5 to 10
knots.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Naylor
AVIATION...Kurz
Area Forecast Discussion
National Weather Service Bismarck ND
930 PM CDT Fri Aug 16 2024
.KEY MESSAGES...
- Areas of wildfire smoke will be found tonight through at least Saturday.
- Patchy fog will be possible across portions of central North
Dakota through the early and mid morning hours on Saturday,
mainly along the US Highway 83 corridor.
- Low to medium (20 to 40 percent) chance for showers and
thunderstorms Saturday morning and again Saturday evening
through the night, mainly across western North Dakota. An
isolated strong storm is possible.
- Temperatures returning to near normal in the 80s this weekend,
possibly warming into the 90s mid next week.
&&
.UPDATE...
Issued at 930 PM CDT Fri Aug 16 2024
For this forecast update, we have decided to include patchy fog
over portions of central North Dakota through the early and mid
morning hours Saturday, mainly along the US Highway 83
corridor. Otherwise, near surface smoke continues to reduce
visibilities across the forecast area. A few showers and
thunderstorms, some of which have been strong to severe, have
formed ahead of an inverted trough in eastern Montana this
evening. While CAMs universally have these storms diminish to
the west of our area, there remains moderate shear and enough
instability along the border to induce us to monitor these
storms over the next few hours. Otherwise, the forecast remains
on track.
UPDATE Issued at 635 PM CDT Fri Aug 16 2024
No major changes to the forecast were made for this early
evening update. Wildfire smoke continues to reduce visibility
across much of North Dakota, with the greatest reductions found
across the north as another push of smoke moves in ahead of
surface high pressure center moving in from the Canadian
Prairies. Cloud cover has also begin to diminish as this high
pressure builds into the region. Winds are generally light, from
5 to 10 miles per hour, and northerly at the time of this
update, though are beginning to turn anti-cyclonically in the
west ahead of the surface high pressure. The forecast remains on
track.
&&
.DISCUSSION...
Issued at 322 PM CDT Fri Aug 16 2024
Clouds continue to linger across central and eastern portions
this afternoon from an exiting upper level low. A few showers
are still possible into the early evening hours across the
southeast. There is enough instability for an isolated
thunderstorm as well in these same areas. Ridge of high pressure
will then diminish clouds through tonight. This will also bring
diminishing winds. Perhaps some fog is possible, although this
will depend on the timing of the clouds clearing, thus
confidence was not high enough to include in the forecast at
this time. Wildfire smoke has settled in across much of the CWA,
and according to the HRRR Smoke will linger through the night.
HRRR smoke then has this smoke lingering across the west and
central for Saturday into Saturday night, although the
concentrations are not as high as today. Have left smoke mention
in the grids through Saturday, even though visibilities should
be slightly improved compared to today. High temperatures on
Saturday will be slightly warming and generally in the mid 70s
to mid 80s. Of interest for Saturday is a low potential for
strong to severe thunderstorms. SPC has added in a Marginal Risk
for Day 2 in western North Dakota. A weak wave and warm front
will lift across the west Saturday morning. MUCAPE is elevated
and shear is also modest to high. Perhaps this could lead to an
isolated stronger storm in the morning, although there is some
doubt on if the forcing from this weak wave will be enough for
stronger storms. Rising heights and warming temps aloft should
limit precipitation chances during the day Saturday. Saturday
evening through Saturday night, the jet stream shifts to over
North Dakota while the warm front stalls. Instability and shear
are still elevated through the night. A low level jet may also
try to set up in the west, although there is some uncertainty to
this. Some CAMs are showing an isolated stronger storm in the
west during the evening and overnight hours. The forcing remains
the biggest uncertainty. For now kept messaging to stronger
storms until more confidence can be found, although there is
enough instability and shear to large hail and damaging winds.
Lows tonight and Saturday night look to generally be in the 50s
to lower 60s. Instability remains elevated through Sunday,
although a ridge of high pressure should bring dry conditions.
Temperatures will generally be in the 80s for Sunday. Smoke
aloft may linger for Sunday, with some uncertainty as to whether
it will reach the surface.
Next week`s weather will still be dependent on the setup of a
interior ridge. If this ridge flattens more over North Dakota,
chances for showers and thunderstorms will return near daily
with perhaps some stronger storms possible. If the ridge settles
more into North Dakota a more dry forecast is expected. NBM is
currently targeting Monday and Tuesday for the chances of
showers and thunderstorms. There remains high confidence this
ridge will bring continued warmer temperatures in the 80s. By
mid week some 90s could also return, especially in the west.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 930 PM CDT Fri Aug 16 2024
Mainly VFR ceilings and VFR to MVFR visibilities are
anticipated across all terminals through the 00Z TAF period.
Widespread near surface wildfire smoke is present across the
forecast area, occasionally reducing visibility to MVFR levels,
and is expected to linger through Saturday. Northerly winds will
generally diminish through this evening, and turning anti-
cyclonically around an area of high pressure at the surface
moving in from the Canadian Prairies overnight. With winds
greatly diminishing across central North Dakota this evening
through early tomorrow, there is potential for patchy fog to
develop across a narrow region running along the Highway 83
corridor, potentially further reducing visibility at the
terminals of KBIS and KMOT in the early to mid mid morning hours
Saturday. This combination of smoke and fog may potentially
promote occasional IFR visibility at these two terminals, though
confidence is currently too low to include such in any TAF at
this time. Otherwise, showers and a few thunderstorms are
anticipated to move into the west Saturday morning. We have
included VCSH at KXWA for this update.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Adam
DISCUSSION...Anglin
AVIATION...Adam
Area Forecast Discussion
National Weather Service Boise ID
836 PM MDT Fri Aug 16 2024
.DISCUSSION...Hotter Saturday as upper winds back from
west-southwest to nearly southerly. Monsoon moisture from
the south will clip Twin Falls County for a 20-40% chance
of afternoon/evening showers and thunderstorms. The rest
of our CWA will be sunny. Similar weather is expected
Sunday and Monday but not quite as hot as Saturday. HRRR
model continues to decrease smoke from the south Saturday
and Sunday, except in and near Boise County where the most
active fires are.
&&
.AVIATION...VFR, except localized MVFR/IFR and mountain
obscuration near wildfires. Gusty southerly winds Saturday,
especially after 20Z. Slight chance of thunderstorms near
KTWF/KJER. Surface winds: variable 6 kt or less after 03Z,
becoming S 10-20 kt with gusts 20-30 kt Saturday afternoon/
evening. Winds aloft at 10kft MSL: S 10-20 kt tonight,
becoming 15-30 kt Saturday afternoon.
KBOI...VFR. Surface winds: NW less than 10 kt shifting
to the SE after 03Z and continuing through Saturday.
Sunday Outlook...VFR, except localized MVFR/IFR and mountain
obscuration near wildfires. Slight chance of aft-eve
thunderstorms with gusty outflow winds in s-central Idaho
(east of KMUO). High density altitude due to hot temperatures.
South-southwest winds aloft of 15-35 kt resulting in gusty
afternoon winds across SE Oregon and mountains of SW Idaho.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Sunday night...An upper low
will remain off the PacNW coast with an upper ridge over the
Rockies. SE Oregon and SW Idaho reside in a southwest flow
aloft between these two features. A slot of dry/stable air
will dominate in the flow, except for s-central ID which
will be near the western edge of monsoon moisture through
the weekend. There is a 15-40 percent chance of afternoon
and evening showers and a slight chance (less than 20
percent) of afternoon and evening thunderstorms each day,
including the Western Magic Valley. Some of the models
indicate the potential for strong outflow winds with the
storms. Breezy to locally windy conditions develop over the
higher elevations Saturday afternoon, enhanced due to the
offshore low. Winds diminish in the evening, but breezy
winds return Sunday afternoon. Hot high temperatures in
the 90s to around 100F in the valleys on Saturday trend
3-6 degrees lower on Sunday.
LONG TERM...Monday through Friday...There may be another
surge of monsoon moisture into portions of southwest ID on
Monday for a chance (20-40 percent) of aft-eve showers/
thunderstorms, mainly in central ID. The remainder of the
area will be under a dry/stable southwest flow aloft. The
upper low off the coast is then expected to move inland
(but well to our north and west) which would at least
temporarily push the monsoon moisture to our east and
provide our entire area with dry conditions from Tuesday
until Thursday. The ensembles favor a southward-moving
upper low off the coast which would transition the flow to
southerly and allow for monsoon moisture to surge back into
portions of southwest ID by the end of the week. Slightly
above-normal temperatures early in the week lower to near
normal by midweek.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning from 1 PM to 10 PM MDT Saturday
IDZ401>403-421.
Red Flag Warning from 1 PM to 8 PM MDT Saturday IDZ423-426.
OR...Red Flag Warning from 1 PM MDT /noon PDT/ to 8 PM MDT /7 PM
PDT/ Saturday ORZ636-637.
&&
$$
www.weather.gov/Boise
Interact with us via social media:
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
SHORT TERM...LC
LONG TERM....JM
AVIATION.....SP
Area Forecast Discussion
National Weather Service Boston/Norton MA
1025 PM EDT Fri Aug 16 2024
.SYNOPSIS...
Dry weather continues for the region Saturday. A slow moving
front will lead to unsettled weather with showers and isolated
thunderstorms Sunday evening through Monday night. Sunday
through Tuesday. A drying trend with seasonable temperatures are
expected for the middle of next week. Meanwhile, Hurricane
Ernesto will track well southeast of New England, but it will
bring rough surf and strong rip currents to south-facing ocean
beaches this weekend.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Stratus was blossoming across southern New England this evening.
Expecting plenty of clouds overnight. Visibility has been fairly
good, so far. Anticipating areas of fog to develop later tonight
as well. Minor tweaks to temperatures. With dew points in the
lower to mid 60s, temperatures should remain nearly steady the
rest of tonight.
8PM Update...
Haze from wildfire smoke has resulted in near total obscuration
of the sky this evening even after lingering stratus dissipated.
While smoke will become less visible after sunset, visibility
will fall as fog develops. HRRR smoke suggests near identical
conditions are expected tomorrow so took the opportunity to add
haze to the weather grids for tomorrow. Estimating that
widespread vsbys of 5-6SM will be observed.
300 pm update...
Other than a few light showers across the Berkshires, dry
weather prevails. Still areas of stratus/low clouds across the
east that should clear out just in time for sunset. Given the
light flow regime we are in, the airmass isn`t any different
than last night, so we should see another round of stratus/fog
develop across most of the area before midnight. Could be some
areas with visibility dropping below 3/4 mile. Overnight lows
should be in the 60s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
300 pm update...
Forecast uncertainty for tomorrow will be how quickly the
stratus and fog dissipates. Given another day with light winds,
it could very well be until noon/early afternoon before it all
dissipates. This in turn could have impacts for how warm it
gets. Went with the guidance blend for highs, so most of the
region should be into the lower 80s. With light winds, sea
breezes will prevail along the coast, keeping temperatures in
the 70s.
As we go into Saturday night, a slow moving frontal system to
our west will start to spread clouds and increasing moisture
into our region. We could see a few showers move into far
western areas late at night. Not looking for any significant
rainfall however.
The prime concern will be the arrival of long-period S to SE
swells from distant Hurricane Ernesto. We have raised a headline
for High Risk for Rip Currents for south facing beaches along coastal
RI, Cape and Islands. This is for the entire weekend. We may
need to expand that to cover the coast of Cape Ann as well. In
addition to the expected stronger rip currents, surf heights
will be elevated. Those heading to the beaches this weekend
need to heed the advice of local lifeguards and beach patrols.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
300 pm update...
Highlights
* Late afternoon and evening showers develop Sunday, with a
chance for an isolated thunderstorm
* Best chance for widespread precipitation comes Monday with a
cold front swinging across southern New England
* Dry, tranquil, and seasonable conditions develop mid next week
Sunday and Monday...
Mid level ridging gradually moves east of southern New England
during the wee hours of Sunday, though it`s slow movement
towards the Atlantic should yield mainly dry conditions for at
least the first half of the day. Warm front lifting ahead of
approaching trough, pushing into the northeast from the Great
Lakes, will likely result in some prefrontal scattered afternoon
showers by late Sunday afternoon. Shower chances will be
greatest across the terrain/interior of SNE, and a rumble of
thunder or two can`t be ruled out either. Will note, however,
that the actual warm front will fall short of our region before
sunset, with the greatest instability remaining to our southwest
across southern NY/NJ/PA, which should mitigate the chance for
severe weather. CSU Machine Learning probabilities have actually
removed the threat for any damaging wind from our region
through 12Z Monday that was present in yesterday`s forecast,
though does show both low tornado and wind probabilities to our
south and west across PA/NY/NJ. Something that we will need to
keep an eye on should the timing of the front change by a few
hours.
Showers become more numerous overnight Sunday into Monday as
trough/cold front are finally able to push into the region.
Preceding warm front lifts north into northern New England which
will allow PWATs to climb to ~1.50"; while moist, nothing to
write home about for mid-August. Anticipate the greatest amount
of rain will fall across interior MA and CT where the
GEFS/ECMWF/GEM probabilities highlight a 30-40% chance of 1" of
rain to fall during the 24 hour period ending Monday night. QPF
probabilities fall off considerably the further east you are in
our CWA, with the chance for 24 hour QPF to exceed a half inch
hovering around 20-40% across eastern MA. Overall, not looking
like this will be a significant rain event, and continue to
suspect, as the previous forecaster stated, the chance for
severe thunderstorms remains low with a lack of shear and
significant instability.
Tuesday and Beyond...
Cold front should be east of the region by late Tuesday, which
will result in an early fall airmass filtering into the region;
dewpoints are expected to fall back into the 50s by late Tuesday
evening. Strong ridging develops across the central CONUS by
mid week but the northeast looks to remain on the eastern edge
of the ridge, with resulting prolonged NW flow. Thus, expecting
a very pleasant, tranquil mid to late week with highs right
around average (70s/low 80s), with low rain chances and
comfortable humidity.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Overall moderate confidence.
The area is stuck in a very weak flow regime, and with no
airmass changes expected, the forecast relies on persistence.
That is, what happened last night should happen again tonight.
Thus, the forecast has widespread IFR ceilings developing in
the 02-06z timeframe. Guidance also indicates that MVFR
visibilities should be fairly widespread. Could drop to IFR in
some locations (ORH, the Cape & Islands). Guidance was not
showing much fog in northern CT, so went along with that, but
it`s possible that forecast does not work out. The low clouds
and fog should slowly dissipate tomorrow morning, and in general
VFR conditions should be developing after 14z. However, like
today, that may end up being later than currently expected.
For Saturday night, we may see some additional stratus/fog
developing in the east to produce some MVFR conditions. May also
have some showers late at night across the far western areas.
KBOS TAF...Moderate confidence. Expecting IFR conditions to
develop overnight, probably similar in timing to last night.
KBDL TAF...Moderate confidence. Should have MVFR ceilings
develop late tonight, perhaps IFR. Uncertainty as to the
development of any fog, though if there is, believe 3-5SM would
be the result.
Outlook /Sunday through Wednesday/...
Sunday: Mainly VFR, with local MVFR possible. Slight chance
SHRA, isolated TSRA.
Sunday Night: Mainly VFR, with local IFR possible. Chance SHRA,
isolated TSRA.
Monday: Mainly MVFR, with local IFR possible. SHRA likely,
isolated TSRA.
Monday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA, isolated TSRA.
Tuesday: Mainly VFR, with local MVFR possible. Chance SHRA.
Tuesday Night: VFR. Chance SHRA.
Wednesday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
300 pm update...
Overall high confidence in the forecast.
Although winds will be 15kt or less over the weekend, Small
Craft Advisories are in effect for the elevated wave heights due
to the powerful swells coming in from the SE due to Hurricane
Ernesto. The swells will also be of very long period (13 to 16
seconds), so this will also result in strong rip currents and
high surf developing along south-facing coast lines. This may
also result in rough conditions at the entrances to inlets and
harbors.
Outlook /Sunday through Wednesday/...
Sunday: Winds less than 25 kt. Local rough seas.
Sunday Night: Winds less than 25 kt. Areas of rough seas.
Slight chance of rain showers, isolated thunderstorms.
Monday: Winds less than 25 kt. Areas of rough seas. Chance of
rain showers, isolated thunderstorms.
Monday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers, isolated thunderstorms.
Tuesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain
showers.
Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers.
Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Air Quality Alert until midnight EDT tonight for MAZ002>004-
008>012.
High Risk for Rip Currents through Sunday evening for MAZ022>024.
RI...High Risk for Rip Currents through Sunday evening for RIZ006>008.
MARINE...Small Craft Advisory from 1 PM Saturday to 8 PM EDT Sunday for
ANZ235-237.
Small Craft Advisory from 7 AM Saturday to 8 PM EDT Sunday for
ANZ254-255.
Small Craft Advisory from 4 AM Saturday to 8 PM EDT Sunday for
ANZ256.
&&
$$
SYNOPSIS...KS/Nash
NEAR TERM...Belk/KS/Nash
SHORT TERM...Nash
LONG TERM...KS
AVIATION...Belk/KS/Nash
MARINE...KS/Nash
Area Forecast Discussion
National Weather Service Billings MT
241 PM MDT Fri Aug 16 2024
.DISCUSSION...
Through Saturday night...
Southwesterly flow will be over our area at 500 mb this evening,
with disturbances moving through the flow and facilitating the
development of isolated-scattered showers and thunderstorms
(20-50% chance). Soundings suggest that main hazards from the
storms will be lightning and erratic wind gusts to about 45 mph.
We are not expecting severe weather at this time due to CAPE less
than 750 J/kg.
Isolated-scattered showers and thunderstorms will be over most of
the area through early this evening, then should be confined to
mostly areas north of the MT/WY border, due to projected shortwave
trough tracks and a low level jet over southeast Montana. After
midnight MDT, shower and storm activity should diminish from west
to east as the second shortwave exits MT to the east and ridging
builds in behind it.
A 500 mb ridge will then dominate our weather for much of Saturday
and Saturday night with dry conditions and mostly clear skies
Saturday and partly cloudy skies Saturday night.
Low temperatures will generally be in the 50s and 60s tonight and
Saturday night, with Saturday night the warmer night. High
temperatures on Saturday will be in the 80s and 90s.
Smoke: HRRR model shows that concentrations will still be greater
to the north and east of Billings, but should decrease over much
of the area through Saturday night. RMS
Sunday through Friday...
Warm to hot conditions with periods of isolated to scattered
showers and thunderstorms will likely persist through next week.
For temperatures, highs are forecast in the upper 80s and 90s
across the lower elevations. For precipitation, the spotty nature
of the activity will cause precipitation to be rather hit or miss
through the period. However, with increased atmospheric moisture
at times, thunderstorms capable of producing locally heavy rain
are possible. The best chance for precipitation across the region
looks to come Monday when there is a 20-80% chance for
precipitation (highest over the mountains and lowest over the
eastern plains). With that, Monday is a day to watch for stronger
thunderstorms as abnormally high CAPE and atmospheric moisture may
be present. Uncertainty remains though, as capping could be an
issue for storm development.
With all that said, there is quite a bit of uncertainty
introduced to the long term forecast during the second half of the
week into next weekend. Part of this is due to Typhoon Ampil in
the western Pacific. As the storm moves north and becomes extra-
tropical over the next few days, this could impact the upper level
weather pattern upstream. This could then transition downstream
into our area. Because of this uncertainty, it is important to
continue to monitor the forecast in the long term if you are
looking at weather for the end of next week. Arends
&&
.AVIATION...
Wildfire smoke will continue to reduce slant range visibility at
times today. With this, KMLS and KBHK will see reductions in
surface visibility below 10 miles at times, with periodic
reduction below 6 miles (to MVFR) possible. Otherwise, isolated
showers and thunderstorms are expected this afternoon and evening
across the area. At this time, confidence is too low to introduce
a thunderstorm to the KBIL and KMLS TAFs. Will amend as necessary.
Any thunderstorm today could produce brief heavy rain and gusty
surface winds. Arends
&&
.PRELIMINARY POINT TEMP/POPS...
Sat Sun Mon Tue Wed Thu Fri
-----------------------------------------------------------
BIL 058/090 063/096 065/094 062/094 061/097 061/090 061/091
20/H 01/U 12/W 21/U 01/U 11/U 11/B
LVM 050/088 056/093 057/090 054/091 055/092 053/089 054/087
30/U 02/T 25/T 31/U 11/U 12/T 12/T
HDN 056/092 061/096 062/095 060/095 060/098 059/092 059/092
20/H 00/U 12/T 21/U 00/U 11/U 11/B
MLS 062/091 065/094 068/093 063/093 064/096 063/091 063/091
22/T 00/U 12/T 31/U 00/U 11/U 11/B
4BQ 060/091 064/095 066/093 063/094 064/097 065/091 064/092
20/H 00/U 02/T 31/U 00/U 11/B 11/B
BHK 058/088 060/091 063/091 060/090 060/093 061/090 061/088
22/T 01/U 12/T 32/T 10/U 11/B 11/B
SHR 054/093 059/095 061/092 058/093 059/097 059/092 058/091
00/U 00/U 03/T 21/U 00/U 11/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
737 PM EDT Fri Aug 16 2024
.SYNOPSIS...
A cold front approaches the Southeast US this weekend, moisture
and rain chances return. Drier air and cooler temperatures are
on tap for early to mid next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):
- Some scattered thunderstorms are possible across the northern
Midlands between 9p-12a.
Scattered-linear thunderstorms are continuing to push southeast
across NC, eventually expected to push down into the Upstate
and potential the Midlands. Water vapor shows the associated
shortwave trough aloft that is triggering this convection with
some modest shear and decent instability. Instability has peaked
across our area, with high temps dropping back down into the
upper 80`s as of 7pm and dew points in the low 70`s; RAP
mesoanalysis paints about 1000 J/kg across the western
Midlands. Surface instability will quickly decrease after about
8pm, and any convection should become elevated as it moves
across the Upstate. HRRR wind swaths support this, with up to 30
mph wind gusts within any line that does stay organized into
the Midlands. All the short range guidance is then consistent in
dissipating any remaining convection across the Midlands
shortly after 04z.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Key Message(s):
- Showers and thunderstorm chances return for the weekend.
- A few thunderstorms may be strong with damaging wind gusts as the
primary severe hazard, particularly on Sunday.
Warm Saturday as upper ridge axis moves offshore and upper trough
moves into the Great Lakes region. Moisture remains high over the
area with PWAT values between 1.7" and 2". Showers and thunderstorms
are expected Saturday in conjunction with a pre-frontal trough with
a cold front still west of the region. Best chance will remain over
the western Midlands closer to the incoming front, mainly in the
afternoon and evening hours. Confidence is on the lower end for
coverage, with a lack of upper support for much of the peak heating
hours. High temperatures Saturday back into the lower 90s, with lows
in the lower 70s.
Better dynamics on Sunday with the front approaching and passing
through the area. Expect additional showers and thunderstorms with
better organization given stronger shear and more upper level
support. Convection could be stronger to marginally severe, mainly
with the threat for damaging winds. Convection may last a little
into the evening hours, but then should end with the front passing
late Sunday night into Monday. Drier air then begins to filter into
the region. Temperatures similar to Saturday, with highs in the low
to middle 90s possible, and lows around 70 Sunday night.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Key Message(s):
- Lower rain chances much of the week with drier air over the region.
Cold front moves east of the area Monday with drier air filtering in
from the west. Upper troughiness hangs around much of the week, but
surface high pressure will translate east across the Great Lakes and
into New England before ridging down the coast mid to late week.
Ensemble mean PWAT values are below 1.5", particularly during the
middle of the week when they may approaching 1". This should set us
up for a drier period along with slightly cooler temperatures, with
highs in the 80s and lows down into the mid to upper 60s.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR Conditions through the period.
With loss of heating this evening the majority of the cu has
dissipated across the taf locations. Further off to the west,
convection across the southern Appalachians will move east and
into the Piedmont through 04z. Most guidance shows this
activity diminishing before moving into any of the taf locations
tonight. HOwever, there should still be some mid and/or upper
level cloudiness moving across the region associated with the
associated shortwave late tonight. VFR conditions will remain
overnight into Saturday. By Saturday afternoon, isolated showers
and storms will begin to develop, but confidence in local
impacts is low at this time. As for winds, light and variable
overnight, then light and possible southwesterly Saturday ahead
of an approaching cold front that will be west of the region.
EXTENDED AVIATION OUTLOOK...Isolated to scattered showers and
thunderstorms are possible Saturday Night and especially
Sunday, primarily during the afternoon and evening hours.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.
&&
$$
Area Forecast Discussion
National Weather Service Quad Cities IA IL
714 PM CDT Fri Aug 16 2024
.KEY MESSAGES...
- Chances of showers and storms will accompany an upper-level
low that will remain anchored over the western Great Lakes
through late Saturday
- A Marginal Risk for strong to severe storms remains over far
northwest Illinois this afternoon and early evening
- A dry pattern develops for next week, with seasonal
temperatures
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 205 PM CDT Fri Aug 16 2024
After abundant sunshine this morning, we are beginning to see some
diurnal cumulus clouds percolating over our region, particularly
across our northern areas as a PVA maxima dives southeastward
towards our area on the southern side of a vertically stacked upper-
level low currently over northern Wisconsin. The main concern with
this approaching trough will be increasing chances of showers and
thunderstorms this PM, especially for areas north of Interstate 80.
Convective parameter space appears to be less favorable for strong
to severe storms compared to yesterday, with MLCAPE values up to
1000 J/kg and 0-6 km shear 25 to 35 knots progged, so a more
marginal environment for strong storms. SPC has maintained a
Marginal Risk (level 1 of 5) for severe storms later on over far
northwestern Illinois, mainly for a wind/hail threat. This activity
should linger into the evening hours before dissipating due to
increasing atmospheric stability.
Calmer conditions are expected tonight once any lingering showers
and storms diminish, but the aforementioned upper low will slowly
slide southeastward toward Lake Michigan Saturday, leading to
increasing clouds tonight and more chances of showers and storms on
Saturday. With the closer proximity of the upper low, there is a low
potential for funnel cloud development from some of the showers. RAP
NST values are fairly meager, with values no greater than 1, which
suggests a pretty low risk of funnels. However, I wouldn`t rule it
out entirely of seeing some funnels under the stronger
showers/storms. Otherwise, instability and shear appears to be more
meager compared to today, so we are not outlooked for any
strong/severe storms. Temperatures are looking pretty seasonal
overall tonight and Saturday, with highs Saturday in the upper 70s
to lower 80s and tonight`s lows in the lower to middle 60s.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 205 PM CDT Fri Aug 16 2024
Although there will be lingering chances of showers and a few
thunderstorms Saturday evening, much of the long-term forecast
period should rather quiet and seasonal.
The upper-level low over the western Great Lakes will finally exit
the region to the east Saturday night, which will lead to a quieter
pattern for us. The WPC cluster analysis indicates a very consistent
signal among the GEFS, EPS, and CMCE ensembles that a large upper-
level omega blocking pattern will develop on Sunday over the central
CONUS and linger through at least Thursday. Upper-level ridging will
become established over the Front Range of the Rockies, placing our
region under an area of subsidence. This will keep our pattern dry
and quiet. Additionally, temperatures will remain seasonal, with
daytime highs in the upper 70s to lower 80s, and overnight lows in
the 50s to lower 60s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 707 PM CDT Fri Aug 16 2024
Large upper level low in the Great Lakes region will spread MVFR/IFR
cigs southward across our taf sites later tonight into Saturday.
Some patchy fog can`t be ruled out late tonight, but confidence
remains low on coverage at this time.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Haase
Area Forecast Discussion
National Weather Service Sioux Falls SD
1042 PM CDT Fri Aug 16 2024
.KEY MESSAGES...
- Low chances (30%) for light showers continues this afternoon,
mainly for areas northeast of a line from Huron, SD to Sioux
Falls, SD to Spencer, IA.
- Could have some light surface smoke tomorrow across the area,
though visibility restrictions are not expected. Biggest
impact will likely be air quality in the orange (for those
very sensitive to lowered air quality).
- Warmer weather with little to no impacts is expected for the
weekend. Continued warm with periodic low rain chances next
week.
&&
.DISCUSSION...
Issued at 252 PM CDT Fri Aug 16 2024
Early afternoon satellite shows an upper level low spinning over the
WI/MN border, with the northwesterly flow advecting stratus across
our northeastern area (mainly SW MN) along with intermittent
scattered showers. At the surface, there is a bit of spread in
temperatures, in the upper 60s under the stratus deck, and up into
the 80s along the MO River Valley. In addition, northwesterly winds
are marginally-breezy, gusting into the 20s and lower 30s. Those
along the MO River will likely get into the upper 80s before
temperatures cool down as a surface high pressure comes sliding down
from the north. This will usher in weaker winds, with overnight
temperatures in the upper 50s/lower 60s.
Looking into the weekend, a ridge of high pressure builds over the
southern plains resulting in geopotential heights rising over the
northern plains. As this occurs on Saturday, a last shortwave from
the upper level low off to our east may result in some additional
showers well east of I-29, but the trend has been to keep things
drier so have omitted mention in the forecast for the time being.
The HRRR and the RAP both show some light surface smoke moving into
the area within the aforementioned surface high pressure, which may
result in air quality being lowered into the orange category
(unhealthy for sensitive groups). Otherwise, the ridging aloft will
result in mostly sunny skies, though if any weak shortwaves along
the ridge develop, cloud coverage could increase as that energy
moves through. This is most probable (<20% chance) for areas in
extreme south-central South Dakota (basically only including Gregory
county) both Saturday and Sunday morning. As for temperatures, both
Saturday and Sunday will see afternoon highs in the upper 70s to mid
80s, with overnight lows in the upper 50s to lower 60s.
Temperatures continue their slow rise into Monday with afternoon
highs in the lower to mid 80s, with general consensus showing the
ridge of high pressure breaking down overnight into Tuesday. This is
due to a mid-level low moving towards the area from the west, which
will bring our next chance (~30%) for light rainfall, with amounts
looking to remain light. Ensembles are currently showing a 50-60%
chance for a tenth of an inch throughout the 24 hour period, though
the NBM only came in with 20-30 pops for each 6 hour period through
Tuesday. Another push of upper level ridging for Wednesday before
the ridge tries to flatten by the end of the week, though troughing
along the west coast will likely build the ridge back
northwards.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1041 PM CDT Fri Aug 16 2024
Quiet conditions continue to prevail across the region. Should see
light and sometimes variable winds prevail overnight, with direction
turning more northerly during the afternoon as sfc high pressure
builds overhead. Otherwise, look for light and variable conditions
to return by the end of the period.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...APT
AVIATION...SST
Area Forecast Discussion
National Weather Service Grand Junction CO
729 PM MDT Fri Aug 16 2024
.KEY MESSAGES...
- Weak monsoon moisture will bring isolated to scattered showers
and storms on Saturday, favoring the mountains and eastern Utah.
- More robust monsoonal moisture will impact the region Sunday
and beyond. Showers and thunderstorms will bring back the
threat of localized flooding Sunday and into the new work
week.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 423 PM MDT Fri Aug 16 2024
Winds in the mountains were gusting at 20 to 30 mph this afternoon
with temperatures running a few degrees above normal. There are
some areas of near critical fire weather conditions this afternoon
with low relative humidity in the lower valleys and across
northwestern Colorado. A deep low dropping into the Pacific
Northwest and a second low shifting east across the Great Lakes
were driving the high over the Southwest eastward into west
Texas. This shift in the pattern opens the door to deep monsoonal
moisture which is expected to move north through Arizona into
eastern Utah and western Colorado Saturday. The return of
subtropical moisture will fuel isolated to scattered afternoon
showers and thunderstorms over higher terrain. Storms strengthen
going into the evening as a shortwave passes to the northwest. The
HRRR continued to be more bullish with this system than the other
models indicating a strong line of storms moving over the
northern two-thirds of the region between 5 PM and midnight. With
the southern edge of the jet overhead and IVT`s in excess of 500
kg/ms over eastern Utah and northwest Colorado driving PWAT`s
above 1", there will be an increased risk for flash flooding due
to localized heavy rain and/or training storms. Not enough
confidence to issue headlines at this time, but this is something
to watch with the next couple runs of the models.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 423 PM MDT Fri Aug 16 2024
Models continue to return consistent agreement on a blocking high
taking up residence over the Rockies this coming week. Despite
several pushes from the northeast Pacific, the ridge remains the
dominant feature here on the West Slope. This regime will set the
stage for monsoonal moisture to work its way under the ridge each
day, producing areas of showers and thunderstorms Sunday afternoon
and beyond. Model agreement remains high that this regime will stay
in place through the extended period. PWAT values 140 to 150 percent
of normal are progged for Sunday across much of the CWA. Ensemble
forecasts are in agreement that precipitable water values stay up
through the week, with some minor deviations thanks to the center of
the high wobbling a bit. Some nocturnal activity is expected to
linger beyond the afternoon into the late evening/early overnight
hours as well. Light steering flow will extend residence time of
storms on their source terrain and thereby increase risks for flash
flooding. Morning lows will trend warm through the period thanks to
elevated dewpoints, while afternoon highs will stick around normal
to 5 degrees warmer than climatology. Some hints are cropping up
that this pattern will shift by Saturday, but likely not enough for
a meaningful break in unsettled conditions.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 729 PM MDT Fri Aug 16 2024
VFR conditions are expected to persist at all TAF sites through
the next 24 hours. Winds will subside early this evening
gradually shifting to a light drainage flow toward midnight. A
surge of subtropical moisture pushes over eastern Utah and
western Colorado on Saturday with storms developing over higher
terrain from late morning through the afternoon. This activity
is unlikely to generate precipitation at TAF sites and ceilings
will be well above ILS breakpoints. Outflow winds from distant
storms could bring brief wind gusts to 40 mph during the
afternoon.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...DB
LONG TERM...LTB
AVIATION...NL
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
748 PM CDT Fri Aug 16 2024
.KEY MESSAGES...
- Isolated (10-20% coverage) afternoon showers and storms linger
through this weekend. Severe weather is not expected, but these
storms will produce localized gusty winds.
- Next work week, dry and seasonably cool conditions will prevail
with no weather impacts expected.
&&
.UPDATE...
Issued at 747 PM CDT Fri Aug 16 2024
This evening, a weak surface trough is noted near the Illinois
River Valley. Latest RAP indicates a narrow ribbon of moderate
instability of 1500-2500 J/kg in the vicinity of this boundary as
it moves across central Illinois late this evening and overnight.
Weak convergence along the front and unfavorable diurnal timing
will limit precip coverage along the front and most of the area
will be dry tonight, but an isolated shower or storm remains
possible. Temps are on track to drop into the mid to upper 60s.
Deubelbeiss
&&
.DISCUSSION...
Issued at 108 PM CDT Fri Aug 16 2024
TODAY-TONIGHT:
At 1pm, temps in the mid 80s and dewpoints in the low 70s were
observed across central Illinois, with west winds around 10-15
mph. While the area remains rain-free at this time, multiple CAMs
from the 12z HREF continue to advertise a brief shower or two
developing at some point during the evening. SPC mesoanalysis
suggests there`s 2000-2500 J/kg SBCAPE in place, and with steep
lapse rates any shower could generate brief gusty surface winds.
However, coverage should be small (10-15%), with most of the area
partly cloudy and seasonably humid (though not as humid as last
night) through the evening.
THIS WEEKEND:
As the upper low lingers to our northeast, lobes of enhanced
vorticity will pass over the Midwest to provide meso/synoptic lift
for a few showers both tomorrow and possibly Sunday afternoons when
low level lapse rates will be steep enough to yield a little
instability (HREF mean is only around 500-1000 J/kg tomorrow north
of I-70). CAMs generally suggest shower coverage will be more (10-
20%, highest I-74 corridor) tomorrow vs Sunday, when instability is
lower as subsidence with an incoming ridge mixes drier air aloft to
the surface. Surface gradients will be on the strong side both days,
and given the aforementioned steep low level afternoon lapse rates,
it will be seasonably breezy with northwest winds gusting 20-25 mph
at times with stronger gusts over 30 mph expected from any shower.
NEXT WORK WEEK:
Models and their respective ensembles suggest the upper trough
responsible for the cool and breezy weekend will take its sweet time
meandering east. In addition, the GFS and ECMWF suggest a closed low
will develop in its wake across the Ohio/Tennessee Valley Region and
sink slowly southward mid-late week. This will maintain northerly
flow and stable conditions through the work week, keeping the area
dry and seasonably cool with NBM probabilities for temps above 80
degF generally lower than 40% (25%) Monday through Thursday (Tuesday
and Wednesday). Looking at the LREF mean 500mb pattern, it appears a
ridge will eventually expand towards the region from the Desert
Southwest, but various cluster solutions imply ensemble spread in
how long it takes the Midwest to start warming back up and to once
again have notable (>15%) precip probabilities; this will likely
be after the end of the forecast period, perhaps late in the
weekend.
Bumgardner
&&
.AVIATION... (For the 00z TAFs through 00z Saturday Evening)
Issued at 606 PM CDT Fri Aug 16 2024
VFR conditions and light W/SW winds 6kt or less are expected to
prevail overnight, though there could be some variability in
direction at times due to the low magnitude. A brief window of
MVFR ceilings may build south towards central Illinois Saturday
morning, but confidence is only high enough at PIA to include in
the forecast. Outside of this potential, expect VFR conditions to
prevail through the period. Winds will shift to WNW mid to late
Saturday morning with some low end gusts of 18-20kt possible
through the afternoon.
Deubelbeiss
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1040 PM CDT Fri Aug 16 2024
.KEY MESSAGES...
- Scattered thunderstorms late this afternoon and evening,
mainly near and north of I-80. A few storms may become strong
to severe with a threat for damaging winds and large hail.
- Scattered showers and isolated to widely scattered t-storms
on Saturday, then isolated to widely scattered showers, and
perhaps a few isolated t-storms on Sunday.
- Long duration of dangerous swimming conditions and hazardous
boating conditions on southern Lake Michigan Sunday-Monday.
&&
.UPDATE...
Issued at 1040 PM CDT Fri Aug 16 2024
Thunderstorms have cleared most of the forecast area as of late
evening, with the exception of our far south and southeast
counties roughly southeast of a Pontiac to Valparaiso line.
These too, should exit the area by or shortly after midnight
tonight. The threat of severe weather has decreased where storms
remain, thanks to low- level diurnal cooling and convective
outflow, though locally heavy downpours and isolated wind gusts
to 50 mph remain possible. Otherwise, skies have become partly
cloudy where storms have exited through increasing cloud cover
is expected to develop from the north overnight.
Ratzer
&&
.DISCUSSION...
Issued at 322 PM CDT Fri Aug 16 2024
Through Saturday Night:
A clear "swirl" pattern is evident in GOES water vapor and
visible satellite imagery this afternoon over the Upper Midwest,
where a vertically-stacked low pressure system is centered at
this time. Along the southern periphery of the low pressure
region, an embedded vorticity maximum can be made out.
Immediately downstream of this vort max, scattered showers and
thunderstorms have blossomed across northeast Iowa and southern
Wisconsin, and the expectation is for this convection to
continue to increase in coverage and intensity as the vort max
steers it our way into an uncapped and increasingly unstable air
mass. Quality low-level moisture has largely remained in tact
here into this afternoon with dew points generally in the upper
60s to low 70s as of this writing, so feel pretty confident
that we`ll get at least a few storms in our forecast area late
this afternoon into this evening, mainly in areas near and north
of I-80, which are positioned closer to the core of the
mid/upper-level low and better large-scale forcing for ascent.
Dry mid-level air has thus far caused our inbound convection to
struggle to take full advantage of the 1000-1500 J/kg of MLCAPE
analyzed in RAP objective mesoanalysis, but if storms can
eventually manage to overcome this dry air, then increasing mid-
level flow going into this evening could enhance shear profiles
enough to support some storm organization, perhaps allowing for
maybe one or two strong to marginally severe storms to
materialize and track across the northern half of our CWA. Most
of this evening`s showers and storms should then depart our area
by midnight, though some straggling spotty showers could hang
around for up to a few hours longer.
The mid/upper-level low will still be in our vicinity come
tomorrow, likely centered over the Lower Peninsula of Michigan.
Its close proximity to our forecast area in conjunction with
steepening low- and mid-level lapse rates should foster another
period of diurnal convective showers across our CWA beginning as
early as the late morning, with peak coverage not expected until
the mid-late afternoon. While lapse rates will not get
particularly steep above 650 mb (where forecast soundings
indicate that a warm nose will be present), equilibrium levels
should still easily exceed the -20C level, so the deepest
convective cells tomorrow will likely contain lightning for a
relatively brief period of time before their updrafts come
crashing down amidst an overall lack of deep-layer shear.
Overall shower coverage should be scattered and generally
greatest across the eastern half of our forecast area, but with
us being only on the periphery of the stronger large-scale
forcing for ascent, the factors inhibiting convective growth and
storm longevity should keep thunderstorm coverage isolated to
widely scattered at best. Shower/storm coverage should then wane
after sunset with the loss of diurnal instability, though lake
effect processes will likely lend a hand in keeping a lingering
stream of broken rain showers going into northwest Indiana
through the night. The daytime showers, associated cloud cover,
and northwest winds should keep high temperatures capped at
about 80F tomorrow.
Ogorek
Sunday through Friday:
The mid-upper level low pressure that will bring diurnally
driven showers and some storms on Saturday will shift into the
eastern Great Lakes on Sunday. While large scale forcing will be
steadily diminishing (mid-level height rises), weak embedded
impulses on the west side of the upper low, lingering mid-level
moisture, and modest destabilization inland of an advancing
lake shadow may yield the development of isolated to widely
scattered showers (highest PoPs 20-40%).
Shower activity should favor inland areas east of I-39 in the
early to mid afternoon. Mid-level moisture will likely quickly
dry out by the late afternoon, causing lingering showers to
dissipate. Regarding thunder chances, generally poor mid-level
lapse rates (5.5C/km or less) are forecast, so with diminishing
forcing and warmer air aloft, expectation is a few isolated
thunderstorms (~20%/slight chance) at most inland. Notably, the
instantaneous lightning flash density product from the 12z ECMWF
kept almost our entire area devoid of any implied lightning.
The slow movement eastward of the weak surface low pressure
associated with the upper low, seasonably strong expansive high
pressure building in from the north and northwest, and relatively
cool air over the warm lake (modest lake induced instability)
will result in an extended period of full fetch brisk northerly
winds Sunday through Monday. Expecting to need a Beach Hazards
Statement and Small Craft Advisory for this period barring a
significant forecast change.
A pseudo-blocky pattern will develop next week, keeping us in
dry northerly mid-level flow aloft between strong ridging over
the southwest and pronounced troughing over northeastern North
America. This will bring dry weather, comfortable temperatures
(slightly cooler by day lakeside), and low humidity through the
work week. Late summer heat may finally make inroads into the
region during the last work week of August.
Castro
&&
.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 605 PM CDT Fri Aug 16 2024
Aviation Forecast Concerns:
- Period of thunderstorms early this evening, with some brief
gusty WNW winds as the storms arrive.
- MVFR ceilings appear likely from late tonight into midday
Saturday.
- Scattered showers and thunderstorms Saturday afternoon and
early evening, especially for Chicago metro terminals.
- Low-confidence potential for winds to shift northeast for
Chicago terminals later Saturday afternoon/evening.
Isolated to scattered thunderstorms were occurring across
portions of far northern IL and WI early this evening. Of note
for the terminals, was a line of thunderstorms currently
stretching from near KMKE to east of KRFD to near KMLI. This
line of storms was moving to the east-southeast at around 35 kt,
and will move into the Chicago terminals shortly after 00Z.
These storms (as well as earlier isolated TSRA across the
Chicago metro this afternoon) have a history of producing gusty
winds, and have indicated the potential for brief 35 kt gusts in
the TAFs. This main line of convection should clear the KRFD
area prior to 01Z and the Chicago terminals by around 02Z. Other
isolated showers upstream are expected to fade with sunset,
making for dry conditions overnight. Model guidance is pretty
aggressive in building MVFR ceilings into the area late tonight
into Saturday morning/midday. No existing extensive deck
upstream yet, but will continue to watch for this development
given good model agreement in its depiction.
An upper level low will continue to drift slowly east-southeast
across the western Great Lakes area through Saturday, with a
couple of smaller mid-level disturbances wrapping around it and
over the region. This looks to support additional diurnal
showers and scattered thunderstorms again Saturday afternoon,
especially across eastern WI/northeast IL including the Chicago
terminals. While TSRA coverage may not be very high, forecast
soundings do indicate enough instability during the afternoon
and early evening hours to message a PROB30 for TS and a
prevailing VCSH.
Breezy west-southwest surface winds early this evening will
ease and turn more westerly later tonight, then eventually
become northwest to north-northwest on Saturday. A couple of
models do suggest a shift to northeast is possible for
KORD/KMDW/KGYY later Saturday afternoon, though confidence is
low at this distance with most guidance NW- NNW. Will have to
monitor this into Saturday.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Marquette MI
731 PM EDT Fri Aug 16 2024
.KEY MESSAGES...
- Scattered to numerous showers and some thunderstorms with
locally heavy downpours through tonight, then showers
diminishing on Saturday into Sunday.
- Mostly dry weather and seasonable temperatures Sunday through
midweek.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 250 PM EDT Fri Aug 16 2024
Water vapor imagery and RAP analyses show a sprawling area of low
pressure spinning over the Upper Great Lakes this afternoon. A dry
slot that worked into the UP earlier today allowed for some
partially clearing skies over the central and western UP, which has
aided in destabilization for those areas this afternoon. Showers and
storms have, in turn, become more numerous there, growing just tall
enough for a good pop of lightning before falling back down again.
Given light wind fields aloft, these are rather slowly-moving, and
with PWATs around 1.5in over the area, our main concern remains
heavy rain. If radar and MRMS rainfall estimates are to be believed,
some of these better-performing cells may feature rainfall rates
around and even in excess of a 0.25in/hr. For rainfall totals the
rest of the afternoon, most of the western and central UP should
receive a widespread 0.25-0.50in of rain, with some isolated spots
(particularly where multiple storms move through) receiving higher
totals in excess of an inch.
Otherwise, with more breaks in the clouds than earlier expected,
temperatures are climbing into the mid 70s across much of the UP. To
the east, however, temperatures are struggling to get out of the 60s
given lingering lower cloud cover there.
As we head into the evening hours and diurnal instability wanes,
expect a decrease in the coverage of showers/storms. With plenty of
low level moisture in place and light winds, patchy fog is expected
to develop tonight, lingering into the early hours of Saturday. Fog
may be locally dense across the western and central UP, where we`ll
have picked up our highest rainfall totals (hi-res ensemble guidance
showing around a 50-80% chance for visibility below a quarter mile
at times). Will hold off on headlines for now, but be weather aware
if traveling early Saturday! With moist, cloudy conditions,
temperatures won`t fall back too much; expect lows in the lower 60s
area-wide.
&&
.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 314 PM EDT Fri Aug 16 2024
Upper air pattern consists of a 500 mb trough and closed low off the
west coast, a trough over the ern U.S. with a low in the Great Lakes
region and a ridge in the Rockies and southern plains and sern U.S.
12z Sat. The ridge builds northward into the northern plains by 00z
Mon with troughing on both coasts which does not change much through
00z Tue. Dries out Sunday into Monday. Did not make too many changes
to the going forecast.
In the extended, the GFS and ECMWF show a deep 500 mb trough on the
east coast with a ridge over the central and southern plains and
Rockies, a trough on the west coast and a shortwave topping the
ridge in the northern plains 12z Tue. Pattern changes little 12z Wed
with ridging building into the upper Great Lakes 12z Thu into 12z
Fri. Temperatures go from near normal to above normal for this
forecast period. Will be dry for most of this extended forecast.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 731 PM EDT Fri Aug 16 2024
Moist airmass and the presence of a stacked low over the region will
continue to support shower and thunderstorm activity for the
remainder of the evening hours. Activity should wane through the
evening though. There may be some redevelopment near KSAW overnight,
but generally, shower activity should diminish tonight. Ceilings and
visibilities are expected to fall tonight to LIFR tonight at all
sites. Its possible KSAW may reach airport minimums, but opted to
stay above that due to lower confidence. Expect some improvement
with daybreak to IFR and some shower activity Saturday.
&&
.MARINE...
Issued at 314 PM EDT Fri Aug 16 2024
Northeast winds of 20 knots or less will continue through tonight
which will continue into Saturday night as the wind backs to the
north. Winds of around 20 knots or less are expected to continue
through the rest of this weekend and early next week as high
pressure ridging moves in. As for thunder storm chances, they look
to continue into Saturday night. Could be some patchy fog across the
lake into Saturday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 10 PM EDT this evening for
MIZ014.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...LC
LONG TERM...07
AVIATION...JTP
MARINE...07
Area Forecast Discussion
National Weather Service Nashville TN
810 PM CDT Fri Aug 16 2024
...New UPDATE...
.UPDATE...
Issued at 804 PM CDT Fri Aug 16 2024
We continue to see showers and a few thunderstorms across our
south and east this evening. These will persist for a few more
hours and shy of giving a few yards some rain, have very little
impact. The rest of the overnight hours should remain quiet once
these storms have exited the mid-state.
Another round of storms is possible tomorrow morning as CAMs have
been pretty persistent in showing development across our southwest
counties around daybreak. Some thunder and brief heavy rain should
come with these storms.
Still not very confident on tomorrow afternoon/evening`s
convective development. There should be some scattered storms
around, at least, so will maintain the 40-50 PoPs currently in the
forecast. Of course, if you`re outside and storms approach, any
storm could have strong gusty winds, so please remain weather
aware.
&&
.SHORT TERM...
(Rest of today through Saturday)
Issued at 1106 AM CDT Fri Aug 16 2024
Earlier convection affecting Middle Tennessee has dissipated, so
there is very little activity occurring across the mid state at
the moment. The HRRR does show some redevelopment during the
afternoon, but it looks to be scattered. So there will likely be
several locations that don`t get any rain today. Also, there are
no plans to expand the existing Heat Advisory any farther east;
the areas that are under the current advisory are going to
struggle to reach a heat index of 105F this afternoon. And
temperatures tomorrow will likely be slightly lower than today`s
so we`re not anticipating any more heat-related products at this
time. Middle Tennessee remains under a marginal risk of severe
storms today and again tomorrow. Strong-to-severe straight line
winds appear the main threat. There is plenty of instability with
this environment, but mid-level lapse rates are anemic due to a
lack of dry air aloft. At any rate, a weak upper trough will
rotate through the region this afternoon, so our storm chances
will drop off considerably by this evening and into tomorrow
morning before storms refire again tomorrow afternoon. Tomorrow,
we can expect another weak shortwave passage to help things along.
&&
.LONG TERM...
(Saturday Night through next Friday)
Issued at 1106 AM CDT Fri Aug 16 2024
Saturday night, the atmospheric models are showing a surface
fropa. So we can expect storms to continue into the night, with
some lingering rain chances on Sunday, mainly over the Cumberland
Plateau. Fortunately, temperatures next week will be more
pleasant, with daily highs and low running a little below seasonal
normals. After Sunday, look for low (or no) rain chances for the
foreseeable future.
&&
.AVIATION...
(00Z TAFS)
Issued at 552 PM CDT Fri Aug 16 2024
Radar trends show scattered showers and storms moving out of
Middle TN with quiet wx and light SW winds expected tonight. Fog
will impact CSV/SRB late night with brief LIFR vsby. Daytime
Saturday will bring mainly VFR conditions with brief impacts from
scattered showers and storms mainly after 18Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 75 94 72 89 / 10 50 50 20
Clarksville 73 93 69 87 / 10 40 50 10
Crossville 67 87 64 81 / 30 40 50 50
Columbia 73 93 71 91 / 30 60 40 20
Cookeville 69 87 66 81 / 20 30 50 40
Jamestown 68 88 65 81 / 10 40 50 60
Lawrenceburg 72 91 69 89 / 40 60 30 20
Murfreesboro 73 93 69 90 / 20 50 50 20
Waverly 72 93 69 89 / 10 50 40 10
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Unger
SHORT TERM...Rose
LONG TERM....Rose
AVIATION.....13
Area Forecast Discussion
National Weather Service Pueblo CO
541 PM MDT Fri Aug 16 2024
.KEY MESSAGES...
- Hot on Saturday, with a slight upturn in thunderstorm chances
over the mountains, mainly along the Continental Divide.
- Monsoonal moisture returns Sunday, with above normal
temperatures and daily chances for showers and thunderstorms
persisting through next week.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 211 PM MDT Fri Aug 16 2024
Currently...Building upper ridge over the area today was suppressing
convection at most locations, and only storms noted at mid-afternoon
were over the OK Panhandle along a weak surface boundary which
slipped through the plains overnight. Despite building
heights/warming mid-levels, afternoon temps have lagged forecasts a
few degf so far today, especially on the plains behind the front.
Tonight...will keep some very low pops going this evening along the
NM and OK border east of Trinidad, as HRRR hints at outflow from
storms to the south potentially forcing a brief/windy storm through
sunset. Elsewhere, expect mostly clear skies and seasonably mild
overnight min temps.
Tonight...Upper ridge continues to build across CO through the day,
with axis drifting slowly eastward toward the KS border by evening.
This set-up should allow at least a minor uptick in available
moisture across the western half of CO, leading to the reappearance
of afternoon thunderstorms, especially along the Continental Divide.
Expect most activity to produce more wind than rain as low levels
will be slow to moisten, with lightning the main hazard with most
storms, especially over any higher exposed peaks. Temperatures
Saturday will climb as heights rise, and maxes deep into the 90s to
low 100s are likely on the plains, with 80s widespread over interior
valleys and lower mountain zones.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 211 PM MDT Fri Aug 16 2024
Saturday Night and Sunday..
Overnight low temperatures on Saturday look to remain around 4 to 7
degrees above normal for most locations, which will give way to
continued above normal temperatures for Sunday. Sunday is a bit of a
transition day though, as models begin to bring a low onshore over
the Pacific Northwest which will eventually push the high off to our
southeast as we get into the beginning of next week. This will open
up the monsoonal moisture tap over our region. For Sunday, models
indicate that the beginning of this monsoonal moisture should start
to work its way into the high country, as we remain situated along
the northwestern periphery of the high. This setup could lead to the
possibility of a few showers and storms pushing into the mountain
adjacent plains through Sunday afternoon and Sunday evening as well,
though the best chances for moisture will remain over the mountains
for Sunday. Daytime highs look to remain around 4 to 8 degrees above
normal for Sunday, though we will see a slight decrease from
expected temperatures on Saturday, especially over and near the
mountains where convective cloud cover will help to keep us cooler
through the hottest part of the day. Our far eastern plains could
still see triple digits under mostly sunny skies, but the majority
of the I-25 corridor should top out in the 90s, with mountain
valleys in the 80s and higher terrain locations in the 70s.
Monday Onwards..
By Monday, models indicate that we transition to a pattern of
slightly above normal temperatures and daily chances for afternoon
showers and thunderstorms, especially over and near the higher
terrain, thanks to the return of monsoonal moisture over the region.
Ensembles, especially GEFS members, show a strong signal for PWAT
anomalies exceeding the 100-140% range beginning Sunday and
persisting all the way through next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 540 PM MDT Fri Aug 16 2024
VFR conditions are expected to prevail for all TAF sites (KALS,
KCOS, and KPUB) throughout the forecast period. Winds will be light
(mostly less than 10 kts) and diurnally influenced at all terminals.
There is low confidence (less than 20 percent) of VCSH and
possible VCTS at KPUB until 02Z. If these do occur, There could
be strong outflows with abrupt wind changes and gusty winds
associated with these, even if tstms do not move directly
overhead. -Stewey
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...PETERSEN
LONG TERM...EHR
AVIATION...STEWARD
Area Forecast Discussion
National Weather Service Springfield MO
631 PM CDT Fri Aug 16 2024
.KEY MESSAGES...
- Slight (2 out of 5) risk for severe thunderstorms this
evening through tonight, mainly over far SE KS and far SW MO.
Damaging wind up to 60-70 mph, large hail up to golf ball
size, and localized flooding are the main severe weather
risks.
- Heat Index values up to 95-105 F remain a hazard today and
Saturday, especially along the Missouri-Arkansas and Missouri-
Oklahoma/Kansas borders.
- 15-30% chance for showers and thunderstorms Saturday evening
and through the night. Large hail and damaging winds are the
main threats. Additional non-severe storm chances Sunday night
(20-40%).
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 325 PM CDT Fri Aug 16 2024
A belt of W`ly upper-level flow is currently setup across the
central CONUS with broad (but rather low-amplitude) ridging
across the western CONUS and a trough dropping SE through the
north part of the Midwest. Between these features, a localized 40-50
kt mid-level jet is spread across NE KS/N MO. At the surface, an
E-W stationary boundary is progged across south-central KS and
MO. Elevated showers and thunderstorms are along and north of
this boundary in central KS, moving east. These have been slowly
dissipating as they move east, but dropping outflow boundaries
in their wake. These features will be the focus for additional
thunderstorm development, with some possibly being severe,
across SW MO this evening into tonight.
Slight risk of severe thunderstorms this evening through tonight:
A lone sub-severe storm along with some other showers are
currently tracking through SE KS. An SPC discussion is out for
this cell, highlighting the possibility for its outflow to
generate new convection within a weakly capped environment
characterized by 1000-2000 J/kg MLCAPE and 40-45 kts of
effective 0-6 km bulk shear. A 40% chance is given for a severe
thunderstorm watch just west of our CWA. If this scenario pans
out, isolated severe storms may enter into extreme SE KS and
extreme SW MO, however, the main chance for higher coverage of
thunderstorms in our region will be later this evening into
tonight.
As the aforementioned trough drops to the SE this evening, flow
aloft will increase and become NW`ly. Synoptic-scale ascent
will overspread SW MO along with this feature. A 25-30 kt
nocturnal LLJ will simultaneously develop and overspread the
stationary boundary draped across the region. Moisture
advection from the LLJ and convergence along the boundary, aided
by large- scale ascent, will force numerous showers and
thunderstorms across SW MO and SE KS (60-80% chance), especially
after 9 PM when the nocturnal LLJ begins intensifying. Isolated
to scattered thunderstorms are still possible (30-40% chance)
before this timeframe (generally in the 6-9 PM timeframe along a
line from Osceola to West Plains and westward), but the highest
coverage will be across the Joplin to Branson area between 12-5
AM tonight where a Slight (2 out of 5) risk is currently
situated.
These storms will largely be elevated with supercells supported,
especially with the storms after 9 PM. HREF mean model
soundings depict larger dewpoint depressions near the surface
above the nocturnal inversion, with ample dry air aloft above
the moist layer. This should favor downbursts with damaging wind
gusts up to 60-70 mph. Additionally, despite largely curved
hodographs in the low-levels overnight with the LLJ, the
elevated storms will effectively create longer and straight
hodographs with 40-60 kts effective bulk shear. This, along with
1000-2000 J/kg MUCAPE largely in the hail-growth zone, and
modest lapse rates at 6-7 C/km, large hail up to the size of
golf balls are also possible with any supercell. Lastly, the
NW`ly flow will largely be parallel to the boundary, so as long
as forcing stays consistent, storms will likely train, bringing
localized flash flooding as another hazard. Areas with storms
will see 1-2" of rain with localized areas up to 3-6". Storms
should be out of the area by 5-8 AM.
Heat Index values up to 100-105 F today and Saturday:
Current obs have temperatures in the lower 90s across the area.
Dewpoints in the lower 70s are contributing to Heat Index values
in the 100-105 range (currently at 100 F in Springfield and 102
F in Joplin). While a Heat Advisory is not issued, heat is still
a hazard given localized areas having values flirting with the
105 F threshold. The same situation will occur Saturday as highs
creep into lower to middle 90s. Heat Index values along the
MO/AR and MO/KS/OK borders are forecast to be near or above 105
F, but given only localized pockets reaching above 105 F along
with uncertainty from leftover cloud cover from storms tonight,
have held off on issuing a Heat Advisory for Saturday.
Nevertheless, heat will still be a hazard and everyone should be
aware of the associated risks and preparedness.
Lows will also be somewhat mild in the middle 60s to lower 70s
tonight and tomorrow night, with the warmer temperatures to the
south.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 325 PM CDT Fri Aug 16 2024
15-30% chance for showers and thunderstorms Saturday night:
With the stationary boundary setting up just to our south and
west, and the nose of a 25-30 kt LLJ revving up during the
overnight hours again, there is a low-end chance (15-30%) for
showers and thunderstorms Saturday night over southern MO. The
main uncertainty is whether forcing along the front will be
enough to overcome right-exit region subsidence aloft.
Currently, all CAMs keep us dry except for the RAP/HRRR, so will
need to monitor trends closely. However, if storms do form, RAP
model soundings support a very conditional threat for very large
hail as mid-level lapse rates are at 7-9 C/km, MUCAPE at
2500-3500 J/kg, and effective bulk shear at 50-70 kts. Damaging
wind gusts up to 60 mph will also be possible. These threats
are on the lower end of the risk spectrum (2-5%).
Additional non-severe storm chances Sunday night (20-40%):
As mentioned in previous, with the NW flow pattern in place, any
source of lift across the surface stationary boundary to our
south and west could force showers and thunderstorms, especially
overnight as the overlapping LLJ intensifies. As such, chances
are on the increase for showers and thunderstorms Sunday night,
west of Springfield. At the moment, severe weather is not
anticipated.
After Sunday night, more rounds of nocturnal thunderstorms are
possible, yet chances dwindle as high pressure strengthens
across the area and the front drops further to the south along
with a sagging trough to our east. This will bring calm weather
next week with highs down into the lower to middle 80s with
lows in the mid-50s to mid-60s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 630 PM CDT Fri Aug 16 2024
Convection has developed across far northwestern Arkansas and
also across central to southeastern Kansas early this evening.
The convection across Arkansas should mainly remain south of the
area. The showers and thunderstorms in southeastern Kansas will
continue to move southeast and move across extreme southeastern
Kansas and southwestern Missouri this evening. Gusty winds,
brief heavy rainfall will occur with the storms. This activity
will likely impact the TAF sites this evening.
Shower and storms will likely continue to develop across
portions so northeastern Oklahoma/southeastern
Kansas/northwestern Arkansas/far southwestern Missouri
overnight. This activity could impact the TAF sites overnight
into early Saturday morning, but questions still remain how far
north this activity overnight develops and if it affects the TAF
sites. As this evenings storms could produce an outflow south of
the area which could be the focus for storms tonight.
Outside the storms VFR conditions are expected through the rest
of the TAF period.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
KS...None.
MO...None.
&&
$$
SHORT TERM...Price
LONG TERM...Price
AVIATION...Wise
Area Forecast Discussion
National Weather Service Tulsa OK
1022 PM CDT Fri Aug 16 2024
...New UPDATE...
.UPDATE...
Issued at 1022 PM CDT Fri Aug 16 2024
Another night of widely scattered storms have developed across
northeast OK and northwest AR. Radar imagery from KINX shows a
distinct outflow boundary drifting S/SW from the main cluster of
thunderstorms. At the moment, the environment remains very
favorable of downburst wind gusts and large hail from the
strongest updrafts. The severe threat is forecast to persist
through at least the next couple of hours before nocturnal
cooling increases convective inhibition. While this may tame the
severe threat some, scattered to numerous thunderstorms will
likely persist beyond midnight as the cluster of thunderstorms
continues to shift southward towards the I-40 corridor/west-
central AR. Recent runs of the RAP and HRRR suggest additional
thunderstorm development behind this cluster after midnight,
mainly affecting northwest AR. Still some uncertainty with how
strong these storms will be beyond midnight. Additionally, PWATs
have increase to around 2 inches in the region. Minor flooding and
isolated flash flooding will be possible through the night,
especially in areas where training sets up as well locations
where heavy rain has already fallen over the last few hours.
A Severe Thunderstorm Watch remains in effect for far
northeast OK and far northwest AR through 11 PM and for west-
central AR through 2 AM.
Mejia
&&
.SHORT TERM...
(Through tonight )
Issued at 210 PM CDT Fri Aug 16 2024
Small cluster of storms keeps chugging along across southern
Kansas this afternoon near a frontal boundary. A very unstable and
weakly capped airmass resides south of the boundary over much of
eastern OK, with DCAPES >1500. Present trends continue to defy CAM
solutions and imply a threat of this cluster eventually moving
into far northeast OK later this afternoon, posing at least a low
threat of damaging wind gusts given the environment south of the
boundary.
Otherwise, dangerously hot and humid conditions persist this
afternoon with heat warnings/advisories continuing through 9 PM.
Still expected re-juivenated convection later this evening north
of the boundary with greatest concentration of storms across NE OK
and NW AR this evening and overnight. Some storm organization is
likely with relatively strong deep layer flow for August, with
damaging wind gusts the primary hazard, but some large hail
potential as well at least initially. Pockets of heavy rainfall
also appear likely, which could lead to localized flooding
potential if heavier rain rates can coincide with locations that
have seen heavier totals as of late.
&&
.LONG TERM...
(Tomorrow through Friday)
Issued at 210 PM CDT Fri Aug 16 2024
Expectation is for convection to be ongoing across mainly NW AR
early Saturday morning. The brunt of organized activity may have
mostly shifted east and south by 12z or shortly thereafter, some
continued rejuvenation of storms remains possible through the
morning within the frontal zone draped across extreme NE OK and NW
AR. The severe threat should be lower at this point, but the
heavy rain threat will continue. Outside of the influence of any
morning convection, dangerously hot and humid conditions are once
again expected Saturday, and additional heat warnings and
advisories have been issued. Notable exception may be the above
mentioned area of NW AR and extreme NE OK where residual cloud
cover may hamper this to some degree. FOr the time being have
kept NW AR out of any headlines, and went with an advisory for the
AR River valley area as confidence is lower in those areas.
Some additional thunderstorm chances continue Late Saturday into
Sunday, primarily across NW AR. Hot weather will continue with
additional headlines likely needed for some areas. Overall the
pattern favors a gradual trend toward not as hot and humid weather
from Monday onward and, whole the forecast does not explicitly
mention any storm chances next week, we do remain on the periphery
of upper ridge with a NNW flow aloft, raising some uncertainty in
keeping a dry forecast. IN any case we will get a break from the
excessive heat, first across NW AR/NE OK, then most everywhere by
mid-week.
&&
.AVIATION...
(00Z TAFS)
Issued at 626 PM CDT Fri Aug 16 2024
An isolated severe thunderstorm has shifted east of KROG with conditions
improving. Additional thunderstorms are expected to develop across
far NE OK/NW AR by late evening with cluster of storms likely
impacting several TAF sites across aforementioned area into the
overnight hours. IFR conditions will be possible in the stronger
storms with very heavy rain/gusty winds. Additional storms may
also redevelop on western flank of activity in convergent zone of
low level jet. Thunderstorm chances are expected to diminish by
mid morning Saturday with VFR conditions for the remainder of the
forecast period.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 76 98 76 96 / 60 10 10 10
FSM 78 97 77 99 / 60 20 10 10
MLC 78 99 76 101 / 20 10 0 10
BVO 71 97 71 94 / 80 20 10 10
FYV 72 94 71 94 / 80 40 10 20
BYV 70 94 70 92 / 80 50 20 20
MKO 75 96 75 96 / 50 20 10 10
MIO 70 94 70 91 / 80 30 10 10
F10 75 99 74 98 / 30 10 0 10
HHW 78 102 77 104 / 0 0 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Heat Advisory from noon to 9 PM CDT Saturday for OKZ054>059-063-
068-072.
Excessive Heat Warning from noon to 9 PM CDT Saturday for OKZ049-
053-060>062-064>067-070-071-073>076.
AR...Heat Advisory from noon to 9 PM CDT Saturday for ARZ019-020-029.
&&
$$
SHORT TERM...14
LONG TERM....14
AVIATION...12
Area Forecast Discussion
National Weather Service Las Vegas NV
817 PM PDT Fri Aug 16 2024
.SYNOPSIS...Dry and breezy conditions can be expected across the
Western Mojave Desert and Western Great Basin through the weekend.
This will be contrasted with increasing moisture and thunderstorm
activity across the eastern Mojave Desert and northwest Arizona,
with locally heavy rainfall possible Saturday in northern Mohave
County. Monsoon storms will tend to retreat into Arizona early
next week before creeping back west midweek onward. Temperatures
will remain a few degrees above normal through the period.
&&
.UPDATE...High clouds and moisture continue to move in this evening
as an inverted trough lifts north through SE California. This
feature brings 20-40% rain chances to Clark, Mohave, and eastern Nye
Counties early tomorrow morning, while Lincoln County has 30-60%
chances throughout most of the morning hours. After this first wave,
attention turns to eastern portions of our area in anticipation of
afternoon redevelopment. Main area of concern is northern Mohave
County, where a Flash Flood Watch is in effect through Saturday
evening. In addition to the flood potential, anomalous vertical wind
shear (~30-40 knots) will increase the likelihood of strong to
severe storms, with damaging winds and small hail possible. Storm
chances linger across SE Nevada and NW Arizona on Sunday, before
getting pushed to the eastern fringes of our area next week as drier
air moves in.
&&
.SHORT TERM...through Sunday night.
Interesting forecast pattern for the upcoming 24 to 36 hours as
the remnants of a westerly propagating shortwave trough along the
international border lifts north and becomes entrained in a broad
south-southwesterly flow pattern across the Great Basin. As it
does so, precipitable water anomalies of 150-200 percent of
normal will spread north across mainly Clark, Lincoln, and Mohave
Counties. This rich moisture will then be acted upon be favorable
jet dynamics and upslope orographics. Overall, this is a weather
pattern more typical of early fall transition events than your
standard monsoon set up, but may lead to some locally strong storm
development late tonight and into Saturday evening.
While the latest few iterations of the HRRR fail to develop much
nocturnal activity tonight, several members of the HREF suggest
convection developing late tonight across southern Mohave and
Clark Counties, and lifting north into Lincoln county prior to
daybreak. While the risk is conditional on storm development,
30-40 knots of deep layer southerly shear would be conducive to
some stronger updrafts capable of small hail and strong outflow
wind gusts. Tend to believe the HRRR is underdone with overnight
development, especially given the magnitude of Integrated Water
Vapor Transport suggested by forecast guidance. Whatever does
develop tonight, will tend to shift into Utah in the morning
hours, though continued moist southerly flow will foster
additional storm development during the afternoon, mainly across
northern Mohave County. With a favorable unidirectional southerly
flow pattern which would favor storm training, and HREF signal
for excessive precip, went ahead and issued a Flash Flood Watch
for northern Mohave County from 12z Saturday morning through 4z
tomorrow evening. Afternoon storm development further west
tomorrow closer to Las Vegas is uncertain, and may struggle due to
post- short wave subsidence, but a few isolated storms may still
develop with locally strong wind gusts and heavy rainfall
possible.
Further west across the Western Mojave Desert and Western edges of
the Great Basin, dry and breezy conditions can be expected both
Saturday and Sunday, with elevated fire danger the primary
concern. A Red Flag Warning remains in effect for Saturday and
Sunday in Esmeralda and Nye counties where fuels and conditions
are at critical risk. Meanwhile, temperatures areawide will remain
above normal, though clouds and precipitation may keep things
fairly close to normal across northern Mohave County Saturday.
Storm chances will persist across our eastern zones into Sunday,
though storm coverage is not expected to be quite as widespread as
on Saturday. Nonetheless, locally heavy rainfall and gusty winds
will remain possible with the stronger storms that do form.
.LONG TERM...Monday through Friday.
Overall weather pattern will change little next week, with dry and
breezy conditions persisting across our western zones and more
moist, convective conditions across our eastern zones. Where
exactly that boundary lies each day is less certain, though NBM
pops do shift noticeably eastward into mainly just northwest
Arizona Monday and Tuesday in response to the flow aloft shifting
more southwesterly. By midweek onward, flow backs to more
southerly again, opening the for for a westward creep of the
monsoonal moisture. Otherwise, temperatures will remain above
normal through the period.
&&
.AVIATION...For Harry Reid...Breezy south to southwest winds will
continue through the afternoon with over a 50% chance for gusts over
20KT through this evening. Winds will diminish tonight with gusts
ending after 03Z then southwest winds around 8KT overnight through
Saturday morning. Southeast winds around 150 degrees will set up
after 15Z Saturday then another round of breezy south to southwest
winds are expected Saturday afternoon. Winds saturday will be
stronger than today with as high probability (80%) for gusts over
20KT and a low probability (20%) for gusts over 25KT.
Most likely, it will be dry through the TAF period with no
thunderstorm impacts at the terminals. There is a low chance for
scattered precipitation to blossom after 09Z tonight through
southern Nevada through early Saturday morning, then another low
chance for thunderstorms to develop Saturday afternoon. Confidence
is currently too low to add convection to the TAFs however will need
to watch how things unfold. If convection does develop late tonight
and/or Saturday afternoon, lightning, sudden gusty winds, and CIGs
10kft are possible.
For the rest of southern Nevada, northwest Arizona and southeast
California...South to southwest winds with gusts of 20-25KT will
continue through the evening. Winds will diminish tonight with
diurnal wind trends expected through Saturday morning. Breezy south
to southwest winds will develop again Saturday with gusts 20-30KT
expected Saturday afternoon in many locations. There is a low chance
(20%-30%) for showers and thunderstorms to develop across Clark and
Lincoln Counties that would push north into central Nevada through
Saturday morning, then another round of convection may develop
Saturday afternoon in northern Mohave County through southwest Utah
and eastern Lincoln. Any thunderstorms that develop would bring the
risk of sudden gusty winds, lightning, heavy rain, and CIGs to 8kft-
10kft.
&&
.FIRE WEATHER...Dry and breezy conditions remain expected across
our western forecast area, namely across Nye and Esmeralda
Counties where a Red Flag Warning is in effect over the weekend.
Elevated fire danger will exist in Inyo County as well, though
fuels are not as critical. Points east across the Eastern Mojave
Desert, Lincoln County, and Northwest Arizona will see increasing
RH today and tonight as a weather disturbance moves through with
chances for rain and thunderstorm activity. Similar conditions
will continue into next week with dry and breezy conditions
persisting across our western forecast area.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Woods
DISCUSSION...Outler
AVIATION...Nickerson
For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter